Elimination of internal reflections and diffractions from junctures in, and at the periphery of, a segmented mirror

ABSTRACT

In a transparent molded segmented mirror having individual sectors on a transparent molding and comprising a myriad of reflecting surfaces at the rear side of the mirror away from the viewer, said surfaces located to produce, in the eyes of the viewer, a virtual image, or separate virtual images from separate portions of such molded mirror, there being zones separating the reflecting surfaces, the improvement comprising: 
     (a) a material coating said zones and which includes a light absorber, 
     (b) such material having approximately, the same index of refraction as the transparent molding, 
     (c) whereby undesirable reflections from said zone are substantially reduced, because light impinging thereon cannot be reflected, but is only absorbed. 
     Also, the thickness of light reflecting metallizing material defining the reflective surfaces may be thinned adjacent said zones, and the light absorptive coating may be applied over the thinned metallizing material; and the edges of the molding and of a glass backer may be coated with light absorptives material.

BACKGROUND OF THE INVENTION

This is a division of application Ser. No. 642,179, filed Aug. 20, 1984,and this application is a continuation-in-part of Ser. No. 385,544,filed June 7, 1982, U.S. Pat. No. 4,470,665 which is a divisional ofSer. No. 233,106, filed Feb. 10, 1981, now issued U.S. Pat. No.4,368,951, on Jan. 18, 1983.

This invention relates generally to mirrors comprising a myriad ofreflecting surfaces so aligned with respect to each other as to produceone virtual image, which may be plain or focused. More particularly, itconcerns mirrors of the type wherein said surfaces are irregular inoutline to minimize or prevent glint patterns. Furthermore it relates tolenses comprising a myriad of lense surfaces so aligned with respect toeach other as to produce one focused image.

This invention may be used in the construction of rear view mirrors (forautomobiles) which afford 160° or greater angle of rear and flank viewsfrom a mirror bracket only somewhat wider than a conventional rear-viewmirror. This mirror will afford an undistorted image through the rearwindow, and smaller virtual images from the left and right flanks andsides of the vehicle.

Most existing mirrors are continuous reflecting surfaces which may betwo-dimensional planar surfaces or three-dimensional curved surfaces(convex, concave or other). Conventional three-dimensional shapedmirrors are bulkier than planar mirrors by virtue of the additionalmaterail needed to provide the third-dimension of the mirror surface.Commercially produced three-dimensional mirrors often have relativelylarge aberrations with attendant distortion of the images reflectedtherefrom. Reducing such distortions would significantly increase thecost of such mirrors.

In the past, mirrors have been proposed wherein multiple reflectingsurfaces, offset from one another, have regular form, as in U.S. Pat.No. 3,739,455 to Alvarez. Due to such repetition of regular outlines ofthe reflecting surfaces, linear glint patterns may be discerned by theviewer. As a result, that type mirror is not well suited to the specialmirror shapes, and uses disclosed herein, as for example rear viewmirrors for vehicles enabling panoramic viewing of one or both rearflanks of the vehicle as well as toward the rear thereof, and otherdevices.

As described in U.S. Pat. No. 4,368,951 to Blom, the reflecting surfaceof a mirror may be segmented, comprising a myriad of reflecting surfacesso aligned or located with respect to each other to produce, in the eyesof a viewer, a virtual image, which may be plain or focused. As with aconventional mirror, the metallized surface of the segmented mirror maybest be located where it is protected, i.e. on the back side of thetransparent part of a mirror assembly, away from the viewer. Themanufacture of such segmented mirrors may be accomplished by molding atransparent material in a suitable die. The die typically has one flatside opposite the side containing the sectors comprising the segmentedmirror.

The main problem with segmented mirrors is that the viewer is botheredby optical interference which originates from the narrow zonesseparating the individual mirror sectors. Light is transmitted withoutdistortion forward through the flat front of the transparent mirrorassembly, and most of the light is reflected without distortion off themetallized sectors at the back of the mirror; however, that portion ofthe light transmitted to the back of the mirror which impinges on thethin zones separating the mirror sectors is reflected and refracted withuncontrolled geometry. These uncontrolled light eminations back towardthe viewer tend to "fuzz" the definition of the virtual image he sees.These aberrations may take the form of linear glint patterns where thesectors of the mirror are in a regular geometric configuration, as inU.S. Pat. No. 3,739,455 to Alvarez. Or the aberration may be morediffuse as in U.S. Pat. No. 4,368,951 to Blom, where the sectors areirregular in outline.

SUMMARY OF THE INVENTION

The main object of this invention is to provide method and means forinsuring that a segmented mirror will produce an image free of undesiredoptic effects related to or resulting from the narrow spaces separatingthe metallized reflective areas. This is accomplished by coating theback of the molded mirror along the narrow zones between mirror sectorswith a light-absorbtive material having an index of refraction,substantially equal to the index of refraction of the transparentmolding. Light incident thereon cannot be reflected or refracted backtowards the viewer from these zones, because it is transmitted into andabsorbed in the coating material. Also the metallizing material may bethinned towards the edge of each reflective area to a monomolecularfeather edge, and covered by the light-absorbtive material ofapproximately the same index of refraction as the material used to moldthe segmented mirror. With this treatment, observable diffractions areprecluded from the periphery of each mirrored sector. If the metalizingmaterial would terminate abruptly at the periphery of each sector, thisperiphery would be a line source of diffractions.

Another object is to apply the metallizing material with diminishingthickness toward the edge of each mirror sector by providing a metallattice having the same shape and width as the lattice of narrow zonesseparating the mirror sectors. This lattice is then superimposed on, andcollated with the molding onto which the metallizing material isdeposited electrostatically. During such deposition the metallizing gasand/or droplets are electrostatically charged with the same polarity asis applied to the metal lattice.

Another object of the invention is to maximize the area of thereflecting sectors, and minimize the area of the narrow zones separatingthe reflecting sectors. In the case of U.S. Pat. No. 4,368,951 to Blom,this entails two actions in making the master die. First, the parallelguide holes formed in the original master block, prior to segmentationthereof, are drilled into the back, inoperative side of the masterblock, such drilling to be terminated before penetrating the operativesurface. Second, the laser beam typically used to cut the originalmaster block into segments is focused to its thinnest dimension at theoperative surface, as will be described.

These and other objects and advantages of the invention, as well as thedetails of illustrative embodiments, will be more fully understood fromthe following description and drawings, in which:

DRAWING DESCRIPTION

FIGS. 1 through 9 show the sequence of steps for making a segmentedmirror, and are separately described as follows:

FIG. 1 is a vertical section through a flat-lying convex glass mirror;

FIG. 2 is a vertical section through a plastic negative casting on theFIG. 1 mold;

FIG. 3 is a vertical section showing laser beam cutting of the negativecasting into segments, the source of the laser beam being perpendicularto a flat plate;

FIG. 4 is a section showing translation of the FIG. 3 segments tocontact a flat glass surface;

FIG. 5 is a section through a die that includes the FIG. 4 segments(immobilized) opposite a flat surface;

FIG. 6 is a positive casting from the FIG. 5 die;

FIG. 7 is a section through a negative die, constructed by using apositive casting from the FIG. 6 die;

FIG. 8 shows the transparent negative plastic casting resulting from thedie in FIG. 7;

FIG. 9 shows the casting of FIG. 8 transparently bonded to a transparentglass plate, with metallized surfaces, i.e., a complete segmented mirrorwhich reflects similarly to a convex mirror. (Actually the angle betweenincident and reflected light is somewhat larger in FIG. 9 than in FIG. 1because of the refraction at the front surface of the glass support.

In FIGS. 10, 11, 12 and 13 each diagram of the plan view of segments ofcastings is the same, because the same pattern of cuts is used each timein the segmentation process. This makes possible the substitution ofsegments to create one collage of two or more groups of segments. Thecollage of segments is then used as in FIG. 4.

FIG. 10 is a close-up plan view of segments of casting (perpendicualr toC-axis);

FIG. 10a is a close-up cross section of displaced facets of segments ofnegative casting (c.f. FIG. 4);

FIG. 11 is a close-up plan view of segments of castings from two groupsof reflection surfaces;

FIG. 11a is a close-up cross section of the facets of segments ofcastings. Slopes to the left are the X group, and to the right are the Ygroups;

FIG. 12 is a close-up plan view of the facets of segments of castings ofR and S groups; S group is cast from a flat plate;

FIG. 12a is a close-up cross section of the facets of segments ofcastings. The R group on the left is in juxtaposition with the S groupon the right;

FIG. 13 is a close-up plan view of facets of segments of castings on theleft in juxtaposition with a casting from a flat plate, trimmed to fit;

FIG. 13a is a close-up of cross section of the facets of the segments ofcastings on the left, and a cross section of a casting from a flat plateon the right;

FIG. 14 shows a mixed junction between two groups of segments ofcastings;

FIG. 15a shows one configuration of a segmented rear view mirror, andFIG. 15b shows in plan the resulting 160° azimuth of rear and flankviews;

FIG. 16a shows a driver's view of a mirror comprising two supportingglass plates, rigidly connected;

FIG. 16b is a horizontal cross section of the mirror in FIG. 16a;

FIG. 16c shows in plan the 190° azimuth of rear and side views affordedby using the mirror pictured in FIGS. 16a and 16b;

FIG. 17a is an elevation showing the advantage of tilting theorientation of the support glass, such that the "ghost" reflection fromthe front of the support glass is from a poorly illuminated area, suchas the ceiling of the driver's cab, thereby making it virtuallyinvisible to the driver;

FIG. 17b is a fragmentary section through the FIG. 17a mirror;

FIG. 18 shows a segmented mirror on a three dimensional support, whichacts as a flat mirror, and shows the versatility of this inventionwhereby the shape of the support is independent of the shape of themaster mirror from which the segments were derived;

FIG. 19 is a plan view diagram of a conventional rear view from amirror;

FIG. 20 is an enlarged cross section through a segmented mirror coatedin accordance with the invention;

FIG. 20a is like FIG. 20 and shows use of a lattice;

FIG. 20b shows formation of the lattice;

FIGS. 21-24 are perspective close-up showings of the steps to insureaccurate displacement of the small segments of a mold (lower block)during their longitudinal translation into positions enabling casting ofa mirror media from the bottom surface of the lower block; and enablingmirror media casting,

FIG. 25, is a side elevation showing details of guiding and peripheralconstriction of irregularly outlined segments of a tabular block fromwhich the lower segmented surface will be used to cast mirror media;

FIGS. 26-28 are not used.

FIG. 29a is a vertical section through a segmented rear view mirrorassembly and mounting joint;

FIG. 29b is an elevation showing the concave interior surface of theFIG. 29a ball housing, showing a raceway groove therein;

FIG. 29c is an enlarged view of the raceway groove seen in FIG. 29b;

FIG. 29d is a further enlarged view showing raceway groove variabledepth configuration;

Each of the groups of figures FIGS. 30a-c, FIGS. 31a-c, FIGS. 32a-c,FIGS. 33a-c, FIGS. 34a-c, and FIGS. 35a-c shows a segmented mirrorconfiguration (see FIGS. 30a and b, FIGS. 31a and b-FIGS. 35a and b) andthe use thereof as a rear view mirror (see FIG. 30c, FIG. 31c-FIG. 35c).

DETAILED DESCRIPTION

Construction of such segmented mirror surfaces is best achieved byforming them from a plastic material, utilizing a die. The plasticmaterial may provide the necessary rigidity, or it may be cast into athin layer (flat on one side and the segmented surfaces on the other).The flat side of the thin layer is then adhered to a dimensionallystable flat material such as glass. The metallized reflecting surfacemay be either the air-reflector interface on which the incident lightfirst impinges, or, if all materials are sufficiently transparent, theimpinging light may travel through these materials and be reflected by amirroring material on the "back" side. The latter generally would bepreferable to protect the metallized surface, and to facilitate cleaningof the exposed surface.

In order to construct a die as seen in FIG. 7, a model as at 10 in FIG.1 with a continuous surface 11 is constructed in the shaped of thedesired reflector. Glass, plastic or some other suitable material may beused for this model, from which a negative copy 12 is molded as in FIG.2 in some suitable material, such as a thermoplastic. This negativecasting 12 is then cut into segments 13 of non-repetitive irregularoutline in such a manner that the orientation of the cutting direction(C-axis) is constant and always the same with respect to the negativecasting. This common direction, as for example vertical, should beapproximately the average direction of viewing of the resulting mirrorsegments by the driver of the vehicle. One convenient manner of cuttingthe casting is with a laser beam 14, the laser 14a held in a jig whichkeeps the beam perpendicular to flat surface 15. See FIG. 3.

After the negative casting is cut into segments, for which perpendicularcross sections are preferably irregular in outline, the segments 13 aretranslated short distances relative to one another, in the same C-axisdirection which is common to all the cut surfaces. The distance oftranslation would be such that the surfaces of individual segments 13 ofthe negative casing each touch the surface to which it is desired thatthey conform, such as the flat surface 15.

It is essential that the segments of the casting are not rotated aroundany axis. Their only movement is translation in the direction of theC-axis, and each segment must retain its same contiguous neighborsegments before and after translation. As long as the segments are keptin contact, translation without rotation of the segments is easily andaccurately accomplished because the elongate segments have only onedegree of freedom of movement with respect to one another, i.e.translation along the C-axis.

The segments are then immobilized with respect to one another, as forexample by bonding the segments 13 with backing material 18, at bondlocations 16, and the resulting stabilized mosaic of displaced segmentsof the original reflecting surface may be used to make a positive dieFIG. 5 (and subsequently a negative die FIG. 7) for manufacturingreplicas of that mosaic surface.

FIGS. 5 and 7 shows dies formed from the FIGS. 4 and 6 structures, andinclude side supports 19 and a flat cover plate 17. Casting spaces 20and 22 are thereby formed between plates 17 and surfaces 13c and 21c ofmosaics 13 and 21, respectively. FIG. 6 shows a casting 21 made byintroduction of plastic into space 20 of FIG. 5, and havingcorresponding mosaic surface 21c which is a negative image of thesurface 13c formed in FIG. 4. The casting 23 may for example consist oftransparent plastic material, such as acrylic, opthalmic plastic orother material. Referring to FIG. 9, the casting may be supported on aglass backer 25, and the mosaic surface will be selectively metallizedat 26, i.e. only surfaces (corresponding to original segments) of afirst group or selected groups will be metallized. The outlines of thesegments should be irregular and without parallel straight line segmentsto obviate the formation of discernible glint patterns. See FIG. 14 inthis regard.

Vehicle Mirror for Rear and Side Views

Conventional rear view flat mirrors afford the driver of a motor vehiclea reflected view of a limited azimuth, restricted by the dimensions ofthe mirror, of the rear window, and distance of the mirror from theviewer. Such mirrors leave "blind spots" on both rear flanks, which thedriver cannot see. This is the cause of traffic accidents when thedriver does not properly monitor and take into account the presence ofnearby vehicles. Convex mirrors are sometimes substituted for flatmirrors to provide a wider angle of reflected rear view vision, butthese mirrors produce small virtual images, and the resolution of thereflected view out the rear window is much inferior to that of theconventional flat mirror. Furthermore, the driver has difficulty injudging distances to objects in the small vitual image. Therefore,drivers sometimes use a convex mirror or mirrors mounted on the sides ofvehicles for flank view(s), as well as a conventional flat mirror, thuscausing the driver to consult two or more mirror brackets to appraisewhat is happening near the rear and flanks of his vehicles. Also, thereare still "blind spots" despite the several mirrors deployed about thevehicle.

By using the principles of the segmented mirror, as described herein, anew type of mirror is provided which will afford an undistorted "flat"reflected image through the rear window as well as small-scale,"condensed" virtual images of both rear flanks of the vehicle, allwithin one rigid structural unit not much larger than that used for aconventional rear view mirror.

One problem for a driver attempting to alternate his attention betweentwo or more mirrors (a flat mirror and convex mirror(s) is that he musttake the time and conscious effort to redirect the azimuth of his visualattention and he must change the distance at which his eyes arefocussed. The focus of his eyes is distant for the flat mirror and closerange for the convex mirror(s). As a person becomes older, this becomesmore of a problem for many drivers because visual redirection andrefocussing takes more time and increased effort. By having all themirror surfaces within one frame, as enabled by the invention, thedriver may glance to the rear view without having to changesubstantially the distance of focus of his eyes from that which he usesfor looking forward through the windshield at the road ahead, while atthe same time his peripheral vision can quickly evaluate whether avehicle is threateningly near either flank of his vehicle. This quickevaluation, without having to refocus to the closer virtual imagesflanking the undistorted view out the rear window, is possible becausethe flanking image of a nearby vehicle moving in the same direction willappear as nearly "stationary" whereas the more-distant middleground willappear to be "flying-by" because of the relatively rapid angularvelocity of objects along the roadside, when viewed by the driver of amoving vehicle via the mirror. This "stationary" look vs a "flying-by"impression is readily perceived by the peripheral vision and thereforethe presence of a nearby vehicle off the flank of the driver's vehicleis easily noted by the driver.

The stereoscopic image one observes with both eyes in a conventionalrear view mirror is augmented by monoscopic continuations of the imageon either side. The left eye extends the reflected image of distantobjects monoscopically to the right by an amount measured horizontallyin the plane of the mirror almost as great as the distance between thepupils of the eyes of the observer. Conversely, the same effect occurswith the right eye. The mind combines the central stereoscopic imagewith the two adjoining monoscopic images into the mental image,comprising the rear view. The observer usually does not realize wherethe stereo portion of the image terminates, i.e. it all registers as oneimage to the observer. See FIG. 19 in this regard.

Optimum Design--Rear View Mirror

One optimum design of segmented rear view mirror, to be located insidethe vehicle near the center of the windshield will include a centralarea derived from a planar surface, and two areas (left and right) forviewing the left and right rear flank views. The width of the entirecomposite mirror is typically about 25 centimeters, and the height about5.5 centimeters, similar to the dimensions of many conventional planarrear view mirrors. The rear flank views should be derived according tothe methods of this invention from areas of master mirrors shapedsomewhat like sections from vertically standing barrels. The "barrelshape" should be sufficiently convex along a vertical plane such thatthe reflected view out the side windows will subtend the entire heightof those windows. The cylindrical curvature should be such that thewidth of each mirror area is about 6 or 8 centimeters for a horizontalazimuth of vision of 60 to 70 degrees.

In order to minimize the width of this mirror, to facilitate thedriver's peripheral awareness of the flank views, and to provide amaximum angle of view for each of the three views (rear and both flanks)visible from the composite mirror, mixed junctions as previouslydescribed (see FIG. 14) perhaps about 1.5 cm. wide, join the centralarea 40 with the flanking areas 42 and 43 of this rear view mirror. Themixed junctions 41 may be slanted, as shown in FIG. 15a, to enhance thedriver's perception of the last glimpse of a passing vehicle, visiblethrough the lower corner of the rear window in many automobiles.

Another optimum design of a rear view mirror made according to thisinvention affords an azimuth of view of 190°, more or less. This isaccomplished by joining two glass backers, such that they form achevronshape in horizontal cross section, with the peak 150 pointedtoward the driver, as can be seen in FIGS. 16a, 16b and 16c. When therear view sections 140 are accurately positioned and immobilized withrespect to one another (FIG. 16a), then the user's mind will perceive anunbroken stereoscopic rear view, and the line 150 marking the joining ofthe two backers will be virtually unnoticed by the driver. The mixedjunction 141 correspond to those at 41 in FIG. 15a, and flank sections142 and 143 correspond to those at 42 and 43 in FIG. 15a.

In the case of a mirror with one glass backer, one would expect that themirror sector for the view of the left flank should subtend a flankingview somewhat wider than for the right flank, as necessitated by thegeometry of the orientation of a conventional rear view mirror to thedriver. However, using the principals of mirror-segmentation embodied inthis invention, the frame of the composite mirror may be oriented toextend the angle of reflected vision more to the right flank (whilecommensurately reducing the angle of left flank vision). This has theadvantage of minimizing any gap in vision between the junction of theforward peripheral vision and the reflected vision of each flank. SeeFIG. 15b in this regard.

In some cases and as referred to above, it may prove advantageous tomake these junctures mixed rather than abrupt. Mixed junctures in theresultant composite mirror are made by mixing reflecting facets fromadjoining families of mirror sectors such that within the zone of mixedjuncture both adjoining mirror families will be represented. Theconcentration or areal density of the number of rear view reflectingsectors of one family may grade from 100% at the edge of that mirrorarea to 0% at the other edge of the mixed juncture. Concurrently thepercentage of sectors resulting from the outer "master" mirror wouldincrease from 0 to 100% across the zone of mixed juncture. Or thepercentage or representatives of each group throughout the zone of mixedjuncture may be constant. See in this regard FIG. 14 with reflectingareas of sets P and Q corresponding to mirror areas 40 and 42, or 40 and43 in FIG. 15a, and the mixed juncture zone (P and Q) corresponding tomirror area 41.

The mixing of groups of facets within the zone of mixed juncture isaccomplished by substitution of appropriate coincident segments of theidentically shaped patterns of negative castings of adjoining groups ofsegments (with common C-axis for all segments). From the resultantcollage a single die is made for the entire composite mirror within thebracket.

The advantage of a mixed juncture (as in FIG. 14) in this case is thatin the zone of juncture within the area of the composite mirror, imagesfrom both the centrally-located flat mirror as well as from the convexmirrors on the left and right sides will be perceived by the driver. Theimage perceived by the driver of an overtaking automobile will be a"nearly stationary" shape blending from a view seen towards the edge ofthe rear window to a smaller "nearly stationary" view out the flankwindow (surrounded by the blurred rush of the background). The mixedjuncture will assist the driver's mind to integrate the two views andrecognize the continuity of movement of the overtaking auto as it movesfrom behind to alongside the flank of the driver's vehicle, until thedriver's peripheral vision directly "picks up" the overtaking auto bydirect view out the side window. Using mixed junctures enables thedesign of a composite mirror which will take up less horizontal width,thereby affording a more unrestricted view by the driver forwardsthrough the windshield, and enabling easier mental assimilation andrecognition of continuity of movement of nearby traffic off both flanksof the vehicle. This is possible because the concurrent views observedby the driver from both flanks are closer together and therefor easierfor the mind to perceive by direct and peripheral observation withminimum shifting or refocussing of the driver's eyes.

However, for the purpose of this invention, the juncture zones betweenthe undistorted central portion of the composite mirror and theoriginally convex flank mirrors may be either smoothly transitional(continuous curvature of one "master" mirror surface, flat in the centerand convexly shaped at both ends), abrupt (sudden change from one mastermirror surface to another), mixed (as described above), or a combinationof these. Each flanking mirror may be junctured so as to minimize theviews of the corner posts and driver, in which case the composite mirrormight have several, n, families of reflecting facets with n-1 juncturezones.

CONSTRUCTION OF THE MIRROR

The first step in constructing the mirror, an example of which is seenin FIG. 15a is to determine the angular subtendance of rear and sidewindows from the vantage point of the intended location of the mirrorinside the vehicle near the upper central area of the windshield. Thecentral portion 40 of the subject mirror is sized and oriented to afforda complete undistorted view through the rear window. For the left andright flanks, suitable convex mirrors 42 and 43 are designed. Thesedesigns should accommodate the transition from reflected views throughrear and flanking windows, so the driver easily may "follow" themovement of nearby vehicles traveling in the driver's direction oftraffic as they pass from view through rear window to rear flankingwindows (or vice versa). The curvatures of the side mirrors 42 and 43may be designed to make the transition gradual from the undistortedcentral reflecting area 40 to the convex flank reflectors. Each sidemirror may be designed with any convex curvature, including spherical orcylindrical curvature, but more likely a complex convex curvaturefashioned to increase the usefullness of the resultant view out theflanking windows.

In order to minimize the width of the "bracket", 44 of the three or moregroups of mirror facets, so as to minimize obstruction to the driver'sview forward and to facilitate peripheral perception by the driver, thecomposite mirror system is designed so that the advantages of each ofthe views are optimized with minimum interference and maximumaccomodation to each other. The optimum relative locations of each ofthe original overlapping "master" mirrors are determined. Castings aremade of each master mirror and the castings segmented, in accordancewith the principals of this invention with a constant C-axis directionof segmentation common to all "master" mirrors. This C-axis directionmust be a constant direction which may be essentially parallel to theline between the point midway between the eyes of an average driverseated in the vehicle, and the central point of the flat mirror(affording a view through the rear window). The pattern of segmentationintended for the finished segmented mirror must be used for segmentingeach of the adjoining master castings. Each such adjoining casting of amaster mirror must be properly located and oriented with respect to theothers such that in the zone of overlap between the sets of segmentsfrom adjoining master castings shares identical segments, enablingselection of a boundary, between the two sets of segments with a snugfit between the adjoining sets of segments.

To construct a lens, using the principals of this invention, a specialmaster lens is used, such as in FIG. 1; however, the design of themaster lens must be such that the negative casting 23 in FIG. 8 has onefocal point for all lens segments. The negative casting 23 is thenadhered to the top surface of a flat glass backer, and/or the positivecasting 21 of FIG. 6 is adhered to the bottom surface of a flat glassbacker to form the lens. The shape of the master lens used for casting anegative die (to control the shape of the "back" surface away from theviewer) must account for the effect of differing indices of refractionon the angles of incidence and emergence of light beams.

In the above description, a casting made from a flat or curvedmirror-smooth surface is segmented to form a master die or mold. Thesegmentation is typically accomplished by cutting the casting intopieces using a laser beam or other device, and then the segments aremoved parallel to the unique direction of cutting (C-axis), so that thesegments all impinge on a surface of the desired shape, usually a flatplane. This process could involve crowding the segments together so thattheir parallel surfaces touch. Such touching should insure that theoriginal orientation of a sector of the mirror surface is maintained inthe orientation of the corresponding segment. However, if the two sideson the cut are not exactly parallel, when they are pressed together thesegments of the casting will not perfectly retain their originalorientation, and thus each segment of the cast surface of the mirrorwill not retain its original orientation vis-a-vis the other segments.In addition, in the process of being crowded together, adjacent segments(cut from convex surfaces) suffer a relative lateral displacement equalto the width of the cut. The resulting mosaic of surfaces, ifmetallized, would yield a reflection with very minor overlaps in theimage around the periphery of each individual surface.

These aforementioned problems may be eliminated in the manner now to bedescribed. Typically, the method involves blocking lateral displacementof the segments while they are translated longitudinally. For example,three or four cylindrical holes or guide openings such as at 201-206 inFIGS. 21 and 22 are drilled (parallel to the C-axis) at locations spacedaround the intended peripheries of the individual surfaces or segmentsbefore segmenting the original casting. See cuts 207-212. After thesegmentation is complete, a straight rod or hollow tube of circularcross section equal in diameter to that of the hole is inserted betweenthe two remaining walls of each hole. See for example rods 213-215 inFIG. 23. After segmentation by cutting parallel to the C-axis, thesegments of the original casting are then translated parallel to theC-axis so that each segment impinges on the surface of desired shape(usually a flat plane as at 216 in FIG. 24). The movement of eachsegment is confined to the C-axis direction, and there is no "crowdingtogether" of the segments, because they are held apart by the rods ortubes of diameter the same or almost the same as the diameter ofopenings 201-206.

The described holes are also useful in ensuring accurate setting of theintended angular relationship between the C-axis and the orientation ofthe surface of desired shape (usually a flat plane), against which eachsegment of the original casting is made to impinge. This is accomplishedby drilling identically located holes in a second rigid sheet or block230 of material into which a number of rigid guide rods are inserted.See guide rods 231-233 in holes 201, 234 and 235 in mold 236, andextending into holes 201a, 234a and 235a in block 230 in FIG. 24. Thelengths of the guide rods extending from the surface of the second sheetor block 230 is such that their ends form a plane 216 of the desiredshape and orientation against which the segments are to impinge. Firstthe guide rods 231-233 are inserted into the corresponding holes whilerods or tubes 213-215 etc. are inserted in the remaining holes. Then themosaic of casting-segments are adjusted i.e. translated to the desiredplane 216. In this regard, a peripheral constriction typically isapplied to the mosaic, immobilizing same, and finally an adhesivematerial which becomes hard is implaced between the mosaic and the rigidblock 230. This forms a rigid block suitable to be surface in a die tobe used in accordance with the principals of this invention. See thelateral constriction means 241 and 242 in FIG. 25, the adhesive material243, in FIG. 25, for example.

From the foregoing, the steps of the method of FIGS. 21-25 include:

(a) cutting irregularly outlined segments of a mold, the segmentsdefining said irregularly outlined surfaces,

(b) and longitudinally translating said segments in said commonlongitudinal direction wile blocking lateral displacement of saidsegments.

In this regard, the step of blocking lateral displacement of the moldsegments includes forming longitudinal guide openings in said mold,prior to said cutting step, to intersect the intended peripheries of theirregularly outlined segments of the mold. Further, the blocking stepmay include inserting longitudinally extending guides into said guideopenings, to guide said longitudinal translation of the mold segments.Certain guides (as at 231-233) may be located to block lateraltranslation of the segments during their translation; and such locatingof the guides may include providing a block as at 230 with locatingopenings therein to receive extensions of the guides.

Pursuant to what has been described above, a segmented mirror may bemanufactured by forming a plastic material utilizing a die. The plasticmaterial may provide the necessary rigidity, or it may be cast into athin layer (flat on one side and the segmented surface on the other).The flat side of the thin layer is then adhered to a dimensionallystable flat material such as glass. By utilizing transparent materials,the metallized reflecting surface may be located on the "back" side ofthe mirror, away from the viewer, as is usually the case forconventional mirrors. This protects the metallized surface andfacilitates cleaning because the exposed surface is flat.

Because the individual mirror sectors of such a molding are aligned witheach other, and spaced from one another, in the same relative positionsas they would occupy in an unsegmented mirror, reflections from themirror sections are perceived by a viewer as coming from an unbrokenmirror which presents the same image as the image from the mirror whichwas cut into segments to make the die. However, part of the area of sucha segmented mirror comprises the narrow spaces separating the reflectivesectors, and the geometry of reflections from these thin areas can notbe comformable with the desired reflections. Therefore the viewer willnotice a certain "fuzziness" in the desired image, which is reflectedcollectively from many mirrored sectors, but interferred with by thedesired incoherent reflections. This problem may be diminished by notmetallizing the narrow zones separating the mirror sectors, as suggestedabove and in U.S. Pat. No. 4,368,951 to Blom.

The problem may be substantially or completely eliminated in accordancewith the present invention by providing, or applying a coating on or atzones separating the reflection surfaces, the coating material includinga light absorber. Referring to FIG. 20, the transparent molded segmentedmirror 300 has a transparent molding 301 produced as described above,and with sectors 302. On the latter are a myriad of reflecting surfaces303a defined as by metallized layers 303 on the sectors at the rear sideof the mirror away from the viewer. Such surfaces are located or alignedto produce, in the eyes of the viewer, a virtual image, or separatevirtual images from separate portions of the molded mirror (as in FIGS.15a and 15b). The zones separating the surfaces 303a are shown at 304.

The material coating the zones 304 is shown at 307. That material may becharacterized as light absorbing, and typically has the same index ofrefraction as that of the transparent molding 301. Accordingly, lighttraversing 302 into zone 304 will be transmitted into the lightabsorbing material 307 where the light will be absorbed and cannot bereflected back to the viewer. The light absorber may comprise a lightabsorptive particulate material such as carbon particles, (as from lampblack) dispersed in a carrier such as a mixture of acrylic, opthalmic orother plastic and solvents. The coating thickness is such that lightincident thereon from the transport molding is absorbed before it can bereflected back to the transparent molding. See rays 308. Coating 307 maybe extended to coat substantially the entire rear side of the mirrorincluding the metallized areas 303.

Another problem arising in the narrow zone 304 of separation is opticaldiffraction from the edge of the metallized surface. If the metallizingmaterial terminates abruptly along the periphery of a mirrored sector,there will be a line source of diffractions along this sharp periphery.This problem can be eliminated, by thinning or tapering the metallizinglayer toward the periphery of each metallized sector, to a "featheredge" of mono-molecular thickness, or only partial monomolecularcoverage. See edges 303a'. This gradual thinning of the metallizingmaterial will create increasing transparency to incident light towardsthis feather edge, and a corresponding gradual reduction in reflectanceof light. This gradation of reflection coefficient will eliminate anysignificant line source of diffractions along the periphery of eachmirrored sector. Potential diffractions from this area can be furtherminimized by coating the back of the zone of thinning metallzingmaterial with the same coating 307 described in the preceedingparagraph, thereby ensuring that incident light can not be reflectedfrom the back of the transparent molding from those minute areas notcovered by metallizing material.

Thinning of the metallizing material around the periphery of each mirrorsector can be accomplished electrostatically. When metallizing materialis applied as a gas or molten droplets as at 313 in FIG. 20a it can becharged oppositely from the molding on which the metallizing material isto be deposited. A lattice, as at 314, patterned after, and superimposedover all the zones of separation in a molding, can be electricallycharged the same as the charge on the metallizing material. This processwill ensure that the metallizing material will be repelled immediatelyaround the charged lattice, with repulsion decreasing with distance fromthe lattice, thus causing the thickness of metallizing material to thinto zero at the edge of each mirror sector. The lattice may be cut from asheet of material with a laser cutter. (See cutter 315 moved along flatsurface 330 and lattice 314 cut by beam 315a in FIG. 20b). The materialof the lattice should be conductive, (as for example copper) to evenlydistribute its electric charge.

The coating applied to the back of the molding, comprising the segmentedmirror, should be applied after the metallizing material is depositedthereon. The coating may either be applied only to the narrow zonesseparating the mirror sectors, or to the entire back of the molding.

To eliminate internal reflections from the edges of the molding, allexterior edges, as at 305, on the sides of the molding should be coatedwith the same material as used on the back of the molding. See edgecoating 307a, which also coats the edge 317a of a glass backer 317 formolding 301.

A molded segmented mirror constructed according to the inventionreflects only from the reflective sectors, and not from the narrow zonesseparating them. To maximize the over-all reflectance of the finishedmirror, the areas treated to be non-reflective should be at a minimum.One means of accomplishing this is adapted for mirrors manufacturedaccording to U.S. Pat. No. 4,368,951 to Blom. First, the cylindricalparallel guide holes drilled in the original master block prior tosegmentation thereof, are to be drilled from the back, inoperative sideof the master block, and drilling is to be terminated before penetratingthe block operative surface. These guide holes are identified as holes201 to 206 in FIGS. 21 through 24 herein and of that patent. Thiseliminates any optic effect from the guide holes because they do notpenetrate the operative or lower surface of block 236, so the holes canbe made larger in diameter, and the thickness of the master block may beincreased. This allows the holes to be more accurate in dimension,straighter and more truly parallel, all valuable attributes for thepurpose of more accurately aligning the segments of the master block tomake the die from which the segmented mirrors will be molded. Also, thelaser cutter used to cut the original master block into segments ispreferably focused to its thinnest dimension at the operative surface,i.e. lower surface of block 236.

Finally, the lattice used to control the distribution of metallizingmaterial should present a target as thin as possible in order that thefeather edges of the metallizing material will extend out to the edgesof the sectors which act as mirrors.

The mirror construction of FIG. 20 may be used in any segmented mirror,including each of the mirror constructions described above, as in FIGS.10-14 for example, and also in mirrors with segments of regular outline,such as squares or hexagons, as described in U.S. Pat. No. 3,739,455 byAlvarez.

FIGS. 30a-c to 35a-c illustrates vehicle rear view mirrors each havingmyriads of reflecting surfaces, as per any of the previously discussedmirrors. Such reflecting surfaces define a plane or planes, and arecontained in a mirror assembly or assemblies, which has or have one ofthe following configurations:

(N₁) convex rearwardly,

(N₂) flat rearwardly,

(N₃) V-shaped with apex facing rearwardly,

(N₄) flat rearwardly, in two offset sections angled relative to oneanother, separated by a mirror surface that is free of said myriad ofsurfaces,

(N₅) convex rearwardly, in two offset sections separated by a thirdsection which is flat, rearwardly,

(N₆) flat and convex, rearwardly, in two laterally spaced sections,respectively, which are separated by a mirror surface that is free ofsaid myriad of surfaces.

Thus, FIG. 30a shows a mirror 500 with its face 501 as seen by theviewer, i.e. the vehicle driver whose head and eyes appear at 502 and502a in FIG. 30c. The mirror frame 523 is suitably supported by strut524. The myriad of reflecting segments include the family of facets 509at the center position of the mirror which permit an undisturbed rearview (see azimuth 515 of rear view in FIG. 30c), the family of facets510 at the left portion of the mirror which permit a condensed view ofthe left flank of the vehicle (see azimuth 516 of left flank view inFIG. 30c), and the family of facets 511 at the right hand portion of themirror, which permit a condensed view of the right flank fo the vehicle(see azimuth 517 of right flank view in FIG. 30c). The reflectingsegments also include metallizing material indicated at 504 on allfacets.

Light absorbing material 503 extends as a layer adjacent to the facetsat the side thereof further from the viewer. A layer of moldedtransparent material 505 defines the facets at the side thereof furtherfrom the viewer. A transparent glass "backer" appears as layer 507bonded to the material 505 via transparent bonding material 506.Incident and reflected light rays appear as shown. The reflected rays asat 508 are directed toward the eyes of the viewer.

Note that the families of facets 509, 510, 511 of the reflectingsurfaces 504 each defines a plane, or the mosaic equivalent of a plane,which is convex rearwardly, i.e. in the direction of arrow 520 directedrearwardly. Families of planes 510 and 511 are each more convex thanFamily 509. Face 501 is also convex rearwardly. Family of facets 509 isso shaped that the driver sees, through the curved backer, anundistorted rear view.

FIGS. 31a-31c are like FIGS. 30a-30c except in this case the family offacets, or the reflecting surfaces, comprising family of facets 609 areparallel, flat surfaces, and the facets in the families of facets 610and 611 are mosaic-equivalents of surfaces which are convex rearwardly.The overall structure is flat, rearwardly in direction of arrow 620. Theelements bear the same numbers as in FIGS. 30a-30c, except that theinitial "5" is now a "6." Face 601 is also flat.

FIGS. 32a-32c are like FIGS. 30a-30c except that the family of facets709 is divided into two sets of facets, 709 left and 709 right, both ofwhich are sets of parallel, flat surfaces so oriented with respect toeach other, that the viewer sees an undistorted rear view without gap oroverlap at 701a. Families of facets 710 and 711 each are amosaic-equivalent to a surface which is convex rearwardly. The overallstructure shown has V-shape, rearwardly. The elements are the same as inFIGS. 30a-30c, except that the initial "5" is replaced by an initial"7". The face 701 is also V-shaped, rearwardly, and has an apex at 701a.

FIGS. 33a-33c are again like FIGS. 30a-30c, except that the left andright wings 801a and 801b of the lopsided chevron-shaped bracket 823meet in a nearly vertical juncture 812, and these wings are flat,rearwardly, with lateral offset surfaces 801a and 801b which meet withangularity α relative to one another. Convex rearwardly families offacets 810 and 811 are separated by a mirror surface 809 that is flatand free of such myriad of reflecting surfaces. Otherwise, the elementsare the same as in FIGS. 30a-30c, except that the initial "5" isreplaced by an initial "8".

FIGS. 34a-34c are also like FIGS. 30a-30c, except that the family orgroup of facets 910 and 911, or reflecting surfaces associatedtherewith, are convex rearwardly, in two laterally offset, left andright sections. Each, in conjunction with refraction of light at therearward surface of the curved glass backer, comprises themosaic-equivalent of a surface which is convex rearwardly. Facets ingroup 909 are flat, rearwardly. Backer face 901 also has two convexitiesat 901b and 901c separated by flat central region 901a. The mirrorelements bear the same numbers as in FIGS. 30a-30c, except that theinitial "5" is replaced by a "9".

Finally, FIGS. 35a-35c are like FIGS. 30a-30c except that the left andright groups of facets 1010 and 1011 of mirror 1000, are themosaic-equivalent of surfaces which are convex rearwardly. They areseparated by a mirror surface 1009 that is flat, and free of such myriadof reflecting surfaces. Otherwise, the elements are the same as in FIGS.30a-30c, except that the initial number "5" is replaced by the initial"10". Backer 1007 is flat over areas 1009 and 1010, and convexrearwardly over area 1011.

Referring now to FIGS. 29a-29d, and also FIGS. 31a-31c, the mirror 600is supported by a ball and socket swivel, as for example ball 560 onbracket 561 suitably attached to the vehicle windshield. Socket 562extends part way about the ball, and defines a gap allowing the socketto swivel relative to the ball. A depression of prescribed shape (on forexample the socket) defines a detent track 563, with raceway groove563a-563d sunk in the socket inner spherical surface, as seen in FIGS.29b and 29c. The track's deepest depressions 564a and 564c are formed attwo raceway corner regions, and a detent follower, as for example pin570 carried by the ball in bore 571, is urged by spring 572 into theraceway. As the mirror and socket are swiveled, the pin guides in theraceway to control such mirror swiveling, and to locate the mirror in aselected fixed position. There are two such positions shown,corresponding to pin sequential seating in the depressions 564a and564c. Control knob 580 appears in FIG. 30a.

In FIG. 30c, head 502 is offset from upright plane 530 bisecting mirror500.

In regard to FIGS. 29 and 30 during night-time use of a segmented mirrorin a vehicle, strong headlights of a following vehicle, when reflectedfrom the segmented mirror, may result in a high light intensitybothersome to the driver. reduced reflection intensity from a segmentedmirror with a flat backer may be achieved by providing the mechanism asdescribed to quickly change the orientation of the mirror assembly sothat the driver sees the view through the rear window reflected from theplanar, non-metallized surface of the mirror assembly nearest to thedriver.

The planar surface of a segmented mirror assembly, if oriented steeplyinclined toward the rear of the vehicle, i.e. upwardly and forwardly, isnot parallel to any of the myriad of metallized reflecting surfacescomprising the mirror. With a segmented mirror of this design the driverobserves the rear and flank views reflected from the metallizedreflecting surfaces, whereas any "ghost reflection" from the rearwardsurface of the mirror assembly may be minimized by inserting a canopy orshade into the field of the ghost reflection as viewed by the driver asdescribed in my co pending application, "Shade for Segmented Rear ViewMirror", incorporated herein by reference. To reduce the reflection ofheadlights with annoyingly high intensity in the following vehicle, theorientation of the mirror assembly may be quickly changed such that thedriver has a low-intensity view out the rear window (but no views ofeither flank). Such a view results from the reflection off the planarnon-metallized front surface of the segmented mirror assembly, when themirror assembly is oriented in the same manner as a conventional automirror. This quick mechanical reorientation of the mirror assemblyrequires that the steep tilt of the mirror assembly be reversed to tiltvery steeply away from the driver, and that the mirror be aligned sothat its perpendicular bisects the angle from the driver via the mirrorto the rear. In this orientation of the mirror assembly, the driver'sview reflected from the metallized mirror surfaces will be directedtoward the relative darkness of the front seat. When the driver againwants to see the full rear and flank views, he can quickly readjust themechanical orientation of the mirror assembly to its original position.

The quick mechanical readjustment of the mirror assembly can beaccomplished to provide only two mirror positions in which the mirrorassembly is at rest. These two positions correspond to the twoorientations 564a and 564c as described above.

The driver of the vehicle may actuate the mechanism for orienting themirror by pulling knob 680 towards himself. This causes the mirrorassembly to move from the initial rest position at 564a. When the pinpasses high point B in the runway, the stored energy in compressedspring 572 quickly rotates the mirror assembly about the horizontal axisas the pin snaps the housing 562 toward the rest position 564c. Thisplaces the mirror assembly in the proper orientation such that thedriver observes low-intensity reflection from planar surface 601. Whenthe driver wishes to return to the original orientation of the mirrorassembly, he pushes knob 680 away until the pin has passed high-point D,and then the mirror assembly quickly is rotated about its horizontalaxis as the pin snaps back into the initial rest position 564a. Theraceway may be Teflon coated; and frame 523 may consist of frangibleplastic material for safety.

I claim:
 1. In a molded segmented mirror having individual sectors andcomprising a myriad of reflecting surfaces on the front side of amolding closest to the viewer, said surfaces oriented to produce, in theeyes of the viewer, one virtual image, or separate virtual images fromseparate portions of such molded mirror, there being a network of zonesseparating the individual mirror sectors, and the sectors beingmetallized, the improvement comprising:(a) the metalizing material beingapplied to the sectors and not to the intervening zones, (b) thethickness of metalizing material being feathered to a partialmono-molecular thickness around the periphery of each sector.
 2. Themirror of claim 1 including a lattice of substantially identical shapeto the network of zones separating the individual mirror sectors, saidlattice being superimposed over and combined with corresponding saidzones of the molding, the lattice, the metalizing material and thesurface of the sectors to be metalized being electrically charged, theelectrical charge on the lattice being the same as the charge on themetalizing material, and opposite from the charge on the surface of thesectors to be metallized.
 3. The mirror of claim 1 including atransparent protective plate fixed in close juxtaposition to the moldingwith the metallized sectors.
 4. The mirror of claim 3 for use in avehicle, and having a transparent cover plate with at least a partiallyflat front surface facing toward the viewer, and having a holdingbracket, the bracket and flat surface having orientation that isgenerally perpendicular, in horizontal section, to the vehicle'sdirection of travel.
 5. The combination of claim 4 including saidvehicle mounting the holding bracket so that a flat portion of saidfront surface is inclined from vertical, being tilted steeply towardeither the rear or the front of the vehicle.
 6. The mirror of one ofclaims 4 and 5 supported in a vehicle cab, and wherein for nightviewing, a flat portion of said front surface is oriented to reflectlight from a rearward source toward the eyes of the viewer, while atthat orientation of the mirror assembly, the myriad of discretemetallized surfaces reflect light towards the eyes of the viewer fromsources in a dark part of the cab.
 7. The combination of claim 6including a ball and socket swivel support for said mirror, one of saidball and socket defining a detent track and the other of said ball andsocket defining a detent follower urged toward and into the track toguide swiveling of the mirror and seek a selected track depression,corresponding to two or more selected fixed pivoted positions of themirror assembly.